Man made airplanes have entered an already inhabited environment, and have to share the aerial medium with various kinds of birds. Encounters between airplanes and birds are not at all uncommon and infect reported bird strike go as far back as a 1905 flight of aviation pioneer Orville Wright. The first casualty did not take long to follow, and a bird strike of aero-pioneer Cal with a gull at 1912 resulted in the crashing of the airplane.
Given the ever increasing number of airplanes at the sky, bird strikes are becoming more of a problem every year. Nowadays, dozens of airplanes suffer bird strikes annually, of which many suffer from physical damage to the airplane while some of these accidents even result in fatal encounters.
On Oct. 4, 1960, Eastern Air Lines Flight 375 flying from Boston encountered a flock of common starlings during takeoff. This incident resulted in damage to all four engines and consequentially to a crashing of the plane shortly thereafter into Boston harbor. Of 72 passengers, 62 people lost their life in this incident.
Annual cost of this problem in the U.S. only is estimated at $400 million and even more. All the more so, bird strikes resulted in hundreds of worldwide deaths. While bird strikes happen most often at low altitudes, and especially during takeoff or landing (or during low altitude flight), the problem is not limited to low altitudes only, and bird strikes occurred at much higher altitudes, even higher than 30,000 feet. It should be noted that bird strikes at low altitudes may not give a pilot sufficient time to recover from the event, and thus crashes are even more likely.
While birds may strike airplanes in various ways, due to the velocity of the airplane which is much higher than that of the birds, birds usually impact airplanes at forward-facing faces of the airplane, such as cone, wing front edges, and most problematically jet engine cowling or inlets. Collisions of birds into engines of airplanes are extremely dangerous, because of the sensitivity of the engines, due to their design, to any significant impact. The fast rotation of the blades only increases that problem. Even more hazardous than encounters with individual birds are strikes by flocks of birds.
Conventional art counter measures are of the following types of solution—design of airplanes or parts thereof to be resistant to bird strikes (e.g. engines of large commercial jet are usually designed to securely shut themselves down after being hit by a bird, and while not designed to operated thereafter, residual damage which may result from displacement of blades for example, is restricted), removal of airplanes from the way of birds (e.g. by education of pilots, by restricting takeoffs and landing in view of birds migration patterns, etc.), and moving birds away of airports and airplanes (e.g. using scaring devices like sounds, lights, decoys, etc.).
It should be noted that conventional art physical solutions have usually been designed to withstand an impact of a single collision with a 1.8 kg bird. It should be noted that the number of passengers and cargo airplanes in the U.S. only well exceeds 6,500, and over 20,000 of them are active worldwide.
There is therefore a great need for effective solutions of reducing damage of birds to airplanes.
High pressure water jets are used in the prior art for cutting and processing machinery. The following documents discuss some examples of prior art use of high pressure jets for cutting and/or processing destination objects in a predetermined manner.
U.S. Pat. No. 6,533,640 discloses an ultra high pressure abrasive waterjet cutting apparatus for cutting nuclear reactor structural components. The cutting apparatus includes an ultra high pressure abrasive waterjet (UHP) cutting nozzle, movably connected to a single axis manipulator, and a collection hood. The manipulator and the collection hood are connected to a support frame and are configured to be positioned inside adjacent apertures of a nuclear reactor top guide or core plate so that the cutting nozzle is in alignment with the collection hood. The manipulator includes a linear frame, a nozzle support plate movably connected to the linear frame, and a motor operatively connected to the nozzle support plate. The collection hood includes an elongate collection chamber having an elongate aperture located so that the aperture is in alignment with the cutting nozzle. The collection hood also includes at least one positioning cylinder connected to the collection chamber and to the support frame which positions the collection chamber aperture adjacent a top guide or core plate beam. The collection hood further includes an outlet port configured to be connected to a water filtration system.
U.S. Pat. No. 7,121,918 discloses a machine tool for processing workpieces using a high-pressure water jet, the workpiece to be processed being mounted on a grate-like or grid-like support over or in a water basin, which is cuboid at least in the upper region, and has at least one water jet exiting from at least one nozzle applied to it, this nozzle being numerically controlled in its position at least in a horizontal plane (X, Y) and the distance between the workpiece and the nozzle being kept at least approximately constant or controlled in the vertical direction (Z) and an equalization container being provided in the region of the water basin, via which the level in the water basin is set, characterized in that at least one side wall on the water basin is designed as partially raisable or foldable and sliding elements, which allow a frame, having workpieces positioned on its workpiece supports, to be moved in and out, are positioned on at least the fixed side walls adjoining this side wall.
U.S. Pat. No. 7,047,857 discloses a machine for cutting the border of a workpiece using one or more water jet cutting tools separately carried by one or more monorail track mounted carriage assemblies. The machine can also include an aperture forming apparatus for forming circular apertures and/or elongated slots in the workpiece prior to/or simultaneously with the border trimming operation, all while the workpiece occupies a single work station in the machine. In one embodiment, the aperture forming apparatus features a cutting tool mounted on an elongate arm affixed to and extending from a plate which is fixedly oriented in a horizontal plane. While so oriented, a motor and gear assembly causes the plate to wobble in a circular pattern in the plane to, in turn, cause the tool to make a circular cut in the workpiece. In another embodiment of the apparatus, a motor rotates a cam carried on a free end of a stationary arm, the cam containing an eccentrically mounted cutting tool.
U.S. Pat. No. 7,008,305 discloses a water jet-processing machine comprising a workpiece holding table for holding a workpiece, a nozzle for applying processing water to the workpiece held on the workpiece holding table, and a processing water supply means for supplying processing water containing abrasive grains to the nozzles, wherein the water jet-processing machine comprises a plurality of the nozzles and an interval adjusting means for adjusting an interval between adjacent nozzles.
U.S. Pat. No. 6,955,107 discloses equipment for cutting particularly a paper web with a water jet. Discussed are support and positioning means and a cutting head supported on them extend in the operating position of the area of the edge part of a paper web. In the cutting head, there is a support surface and at least one nozzle, which is set in such a way that the edge part travels between the support surface and the nozzle. The equipment includes mechanical cleaning means and/or a cleaning construction for keeping the support surfaces clean. The cleaning means and/or cleaning construction are arranged on the opposite side of the paper web to the nozzle.
U.S. Pat. No. 5,839,927 discloses a water jet system that uses cantilever bars for an inlet grating, to prevent blockage. The water jet system also uses an elliptical impeller shaft housing to reduce turbulence and snagging of debris by the rotating impeller shaft. The water jet system uses impeller blades with a curved cross section that curves towards the direction of forward rotation. The water jet system uses U-shaped flanges mounted to the outlet of the water jet to provide steering.
U.S. Pat. No. 5,018,317 discloses an abrasive water jet cutting apparatus. In an apparatus for cutting a work by an abrasive water jet containing abrasive particles, an abrasive suspension such that abrasive particles with an average size of up to about 1100 microns are held in suspension in water is supplied to a jet nozzle assembly in which the abrasive suspension is induced by a high pressure ejected water and directed against the work. The ejected water is passed through an ejected water passageway to which is connected an abrasive water orifice of an abrasive water nozzle tip. The abrasive water orifice has an upstream tapered portion the diameter of which gradually increases toward an upstream aperture at which the abrasive water orifice is connected smoothly to the downstream end of the ejected water passageway, whereby the flow of ejected water is streamlined. The abrasive suspension is supplied to, and merges with, the streamlined flow of the ejected water near the junction of the ejected water passageway and the abrasive water orifice, as an outer layer of the streamlined flow, whereby a dual-layer streamlined jet is obtained which enables fine cutting and also reduces wear of the nozzle tip.